The present invention relates generally to new and novel improvements in porous inking members for impact printers and methods of making the same. More particularly, the present invention relates to porous inking members for impact printers and methods of making the same which are particularly suitable for retaining ink and providing a controlled uniform rate of ink transfer flow from the porous inking members to dot matrix and other impact print heads resulting in increased numbers of legible printed characters and images and enhanced useful porous inking member life.
Porous inking members have found wide acceptance as an easy to use and relatively inexpensive source of printing ink for dot matrix and other impact printing operations carried out by a variety of printers. Such porous inking members generally produce dark printed characters and images when new, but the darkness of the printed characters and images gradually fades as the ink originally present in the porous ink member is consumed during the printing process.
It is generally desirable to reduce the rate of fading of printed characters and images produced from porous inking members and thereby extend the useful life of the porous inking members. Such porous inking members generally consist of a cylindrical porous rubber or foam member which is impregnated with a liquid ink. The liquid ink is transferred from the porous inking member to the dot matrix or other impact print head through either direct contact between the porous inking member and the dot matrix or other impact print head or, more often, through indirect contact by use of a transfer roll positioned between the porous inking member and the dot matrix or other impact print head.
The process to manufacture such porous inking members generally involves the use of volatile organic solvents, such as toluene. However, the use of such volatile organic solvents can present not only an air pollution hazard, but can also have the potential to impair the health of workers. In order to reduce or eliminate the use of volatile organic solvents, such as toluene, efforts have been made to investigate alternative materials or methods to manufacture porous inking members. Several other manufacturing processes are known for making porous inking members, such as the thermoplastic resin method, the thermoset polyurethane forming method and the thermoplastic polyurethane extrusion method. However, all of these known prior art porous inking member manufacturing processes involve the use of hazardous substances and/or expensive equipment.
Accordingly, an object of the present invention is the provision of porous inking members for impact printers and methods of making the same which do not use volatile organic solvents, such as toluene, in the manufacturing process.
Another object of the present invention is to provide porous inking members for impact printers and methods of making the same which eliminate the organic solvent evaporation cycle in the manufacturing process.
A further object of the present invention is to provide porous inking members for impact printers and methods of making the same which provide more flexibility in the manufacturing process by having increased material storage and shelf life following the step of mixing the ingredients and prior to the step of transfer molding.
Still a further object of the present invention is to provide porous inking members for impact printers and methods of using the same which provide a relatively uniform rate of ink transfer resulting in increased numbers of legible printed characters and images and thus enhanced useful service life.
Yet another object of the present invention is to provide porous inking members for impact printers and methods of using the same which are safer to manufacture in terms of workers' health and the environment.
Still yet another object of the present invention is to provide porous inking members for impact printers and methods of using the same which maximize the use of existing manufacturing and production equipment and engineering expertise.
These and other objects of the present invention are attained by the provision of porous inking members for impact printers and methods of making the same which control the ink transfer flow rate from the porous inking members to dot matrix or other impact print heads. One preferred embodiment of the porous inking members for impact printers and methods of making the same uses peptizer and liquid nitrile rubber as ingredients in the manufacturing process to produce porous inking members.
Other objects, advantages and novel features of the present invention will become apparent in the following detailed description of the invention when considered in conjunction with the accompanying drawings.